1. Field of the Invention
The present invention relates to a lens tube and a mounting base thereof, wherein a first conical surface of the lens tube and a second conical surface of the mounting base cooperate with each other, so as to prevent dust contamination and to make the central axis aligned with the optical axis.
2. Description of the Prior Art
The existing lens tube 10 and the mounting base 11 thereof is shown in FIG. 1, in the lens tube 10 is formed a passage 12 in which being inserted a lens array 13, and the optical axis a of the lens array 13 is in alignment with the optical axis b of the passage 12. By such arrangements, the optical signal of the object to be shot will be focused on the image sensor 14 after passing through the lens array 13. In the passage 12 are formed a plurality of inner threads. In the mounting base 11 is defined a passage 12 and on the outer periphery of the passage 12 are formed a plurality of outer threads for mating with the inner threads of the lens tube 10. The abovementioned arrangements can prevent dust from falling on the image sensor 14 when the lens tube 10 is assembled on the mounting base 11, affecting the image quality, however, it still has the following defects that need to be improved:
First, the lens tube 10 and the mounting base 11 are screwed together in a single thread manner, so that the optical axes a and b are likely to deviate from each other if the inner and outer threads are not engaged appropriately, or due to the wobbles of the lens tube 10 with respect to the mounting base 11, and as a result, the optical signal will not be transmitted to the image sensor 14 precisely, causing fogging image or halation.
Second, sine the lens tube 10 and the mounting base 11 are screwed together in a single thread manner, clearance will occur at the engaging portion between the lens tube 10 and the mounting base 11 after long time of use. And the clearance will be increased once it occurs, the optical axis a will deviate from the optical axis b, so that the optical signal of the object to be shot cannot be projected as desired onto the image sensor 14.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.